New poll shows Trump behind Clinton

Two new national polls are out and both lend more evidence to the theory that Hillary Clinton's lead over Donald Trump is becoming the norm.

In a four-way race between Clinton, Trump, Gary Johnson and Jill Stein, both Pew Research and Rasmussen Reports found the former secretary of state wins out with 41 percent of voters supporting her and Trump garnering 37 and 39 percent, respectively.

These aren't all that different from what we've seen lately. Trump's having a rough stretch both nationally and in key battleground states like Florida, Pennsylvania and the Republican must-win, Ohio.

And this is bad news for Trump because, historically, every nominee winning at this point in the process since polling was invented has gone on to, at the very least, win the popular vote. An expert put it this way to Politico, "When you come out of the conventions, the leader in the last 16 elections has not lost the popular vote."

That's for a couple of key reasons. The first makes the most sense: The closer you get to the election, the more people begin to pay attention and start cementing their decision for November.

That then causes the second reason, which is that the post-convention bump nominees usually enjoy goes away and we get a better sense of what the electorate is thinking. Now, it's not impossible for Trump to turn it around, but based on his past behavior and insistence that he's not changing, getting new voters is going to be difficult. But throw in the fact that Clinton is also having a trustworthy deficit in polls, and 2016 could be ripe to change the historical polling trend.

The best way for Trump to diversify his support is to kick serious ass in the presidential debates over the next couple of months. But it's not clear, at this point, if he's even going to participate.

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Mitt Romney has been critical of Trump's rhetoric. REUTERS/Jim Urquhart

Senator John Thune (R-SD) addresses delegates during the third session of the Republican National Convention in Tampa, Florida, August 29, 2012. REUTERS/Mike Segar (UNITED STATES - Tags: POLITICS ELECTIONS)

Jeb Bush, former Governor of Florida and 2016 Republican presidential candidate, was one of Donald Trump's primary targets during the primary season.

Daniel Acker/Bloomberg via Getty Images

Former Republican presidential candidate and Ohio Governor John Kasich stayed in the primary longer than most other candidates, and notably refused to appear at the GOP convention in the same arena with Trump, attending other events instead. (Photo by Alex Wong/Getty Images)

Sen. Lindsey Graham (R-SC), a close friend to Sen. John McCain, has been a vocal critic of Trump's. (Photo by Drew Angerer/Getty Images)

UPDATE: Although he didn't endorse Trump during the 2016 convention, Ted Cruz eventually changed his mind, saying in September he'd vote for the GOP nominee (Photo by Ida Mae Astute/ABC via Getty Images)